Golden-boy Brody gives his girlfriend, Alexis, a promise ring, excited for her to finally meet his older sister, Becca, at the prom. But when Alexis mistakes Becca for Brody's mistress, she and her clique brutally humiliate her in the ballroom. After Brody reveals the truth, Becca rises to demand justice, turning the prom into a reckoning where every bully, accomplice, and bystander must pay.